锡林浩特草原CO2通量特征及其影响因素分析

利用锡林浩特国家气候观象台开路涡度相关系统、辐射土壤观测系统,测得的长期连续通量观测数据,对锡林浩特草原2009—2011年期间的CO₂通量观测特征进行了分析。结果表明:CO₂通量存在明显的年际、季节和日变化特征。3 a中NEE年际变率达到200 g·m^-2,季节变率最大达到460 g·m^-2,日变化幅度生长季最大达到0.25 mg·m^-2·s^-1。通过不同时间尺度碳通量与温度、水分、辐射等环境因子的分析,认为CO₂通量日变化主要受温度和光合有效辐射影响,而季节变化和年变化主要受降水和土壤含水量的影响。降水强度及时间分布是制约牧草CO₂吸收的关键因素,大于15%的土壤含水量有利于促进牧草生长。

Observing characteristics of CO2 flux and its influencing factors over Xilinhot grassland

Based on the continuous measurement of surface fluxes data by eddy covariance during 2009-2011 from Xilinhot National Climatological Observatory, the characteristics of CO₂ flux and its influencing factors were investigated. Results show that diurnal, seasonal and annual variation characteristics of CO₂ flux are obvious. The annual variation rate in three years of NEE reaches 200 g·m^-2, the maximal seasonal one amounts to 460 g·m^-2, and the maximal daily variation amplitude in growth seasons is 0.25 mg·m^-2·s^-1. Analysis on carbon fluxes and meteorological factors such as temperature, water and radiation at different time scales shows that daily variation of CO₂ flux is mainly affected by temperature and photosynthetically active radiation(PAR), while annual and seasonal variations are chiefly influenced by precipitation and soil moisture content. The intensity and time distribution of precipitation are the key factors to CO₂ flux. Soil water more than 15% will promote the growth of herbage.